The overall objective of this work is to further our understanding of the functional organization of the normal adult human brain. Such an undertaking is feasible for two reasons, (1) PET can measure changes in blood flow in small regions of the normal human brain with a degree of accuracy unsurpassed by any other technique and (2) changes in local blood flow accurately reflect changes in the activity of local ensembles of neurons. The vasculature provides a unique "window to the workings of the brain". Using PET measurements of local brain blood flow we will (1) identify multiple sensory areas in the human cerebral cortex of individual subjects in relation to their MRI-defined anatomy; (2) define, at least coarsely, the topographic organization of these areas; (3) test stimuli which will serve to identify functional landmarks within the cerebral cortex; (4) determine how more complex functions like language are mapped on to these principal areas; (5) test the relationship of functional vs anatomical landmarks in primary sensory areas; and, if there is not a tight relationship between anatomical and functional landmarks, (6) test the use of functional landmarks as constraints in 3- dimensional warping algorithms in order to enhance signal averaging and comparisons of functional maps across subjects.